From the prior art, milling devices are known which comprise a machine-frame-supported milling rotor that is arranged transverse to the working direction. In milling operation, such milling devices traverse overground, with the milling rotor submerging in the ground and milling off the soil material with the help of the milling tools arranged on the rotating milling rotor. In milling operation, the milling device thus moves in the working direction and traverses over the soil to be processed. Typical areas of application of such milling devices include road and pathway construction, for example, in the form of road milling, and the removal of soil material, e.g. in open-cast mining operation. Such milling devices are also preferably designed as self-propelled machines, thus eliminating the need for separate towing vehicles.
An important aspect in the operation of such milling devices is the handling of the milled material, i.e. the material milled by the milling rotor. In many areas of application, it is necessary that the milled material is transported away from the milling location by means of a suitable transport device, for example, a truck. To this end, the milling device usually has a conveyor by means of which the milled material can be transported during the milling operation of the milling device from the area of the milling rotor to the transport container of the transport vehicle. Here, various embodiments are known in regard to the specific arrangement of the conveyor device in relation to the transport vehicle. Apart from the possibility that the conveyor transports the milled material—relative to the working direction of the milling device—to the rear (“rear-loader”) or to the side (“side-loader”), a conveyor belt directed to the front (“front-loader”) has particularly proven suitable for milling devices designed as road milling machines. The latter has the advantage that during milling operation the transport vehicle may drive in front of the milling device on the ground still to be milled. However, especially this loading type normally places stricter requirements on the milling machine operator. For example, in particular the visibility of the preceding transport trucks is poor and the milling machine operator cannot see the loading trough completely, for instance. The driver of the transport truck cannot see the loading conveyor either. This is especially true when the visibility is also impaired by the local conditions, as is often the case in road construction, for example, due to road curves, narrow roads, traffic flow in the surroundings, ground obstacles, such as manhole covers, etc. In addition, the milling machine operator bears the responsibility for safe work process, particularly with regard to road safety and personal safety. Further, for proper removal of the milled material, precise control of the loading process is desirable. On the one hand, the milled material, which is often milled pavement, has a relatively high density, which can quickly lead to overloading. On the other hand, the transport trucks commonly used here move at speeds of up to 100 km/h, so that the overloaded vehicles may pose a particularly high safety risk.
The fact that the milling device in the working or milling mode is usually in driving operation, that is, it moves along in the working direction, the transport vehicle cannot remain at one place over the entire loading process. It must rather move with the milling device along the working direction in order to remain within the loading range of the conveyor. Since the milling device in milling operation often moves relatively slow, repeated starting and stopping of the transport vehicle has established, which at the same time particularly also allows for uniform loading of the transport container of the transport vehicle. This process will be explained in further detail below, by examples of the operation of a front-loader road milling machine.
In milling operation, for this purpose, a transport vehicle with a transport container travels ahead of the milling device and receives the milled material via the conveyor. The coordination of the moving milling device and the moving transport vehicle is of particular importance here. On the one hand it has to be ensured that the milled material can be dropped from the conveyor into the transport container of the transport vehicle. On the other hand, it is necessary to prevent a collision of the two vehicles during milling and loading operation. Presently, the responsibility for coordination of the relative position of the transport vehicle to the milling device is essentially borne by the operator of the milling device. This operator continuously monitors the distance of the milling vehicle to the transport vehicle and alerts the driver of the transport vehicle continuously by issuing the commands “move forward”, “stop”, and “depart” for adjusting the position of the transport vehicle relative to the milling device moving in milling operation along the working direction. This usually happens via an alarm signal. Specifically, the milling device moving at essentially constant working speed approaches the transport vehicle up to a minimum distance. The machine operator then issues the “move forward” command, until the transport vehicle has driven forward to the maximum distance for the loading operation and causes the transport vehicle to stop with the command “stop”. The maximum distance is the distance between the transport vehicle and the milling device still just allowing the conveyor to discharge the milled material to the rear area of the transport container, without significant amounts of the milled material falling to the ground behind the transport container. The minimum distance is accordingly the distance at which the conveyor is still just able to discharge the milled material to the front area of the transport container or at which the milling device does not collide with the transport vehicle yet, whichever distance is greater. Once the transport container of the transport vehicle has reached its specified fill, which is also monitored by the milling machine operator, the operator indicates completion of the loading process with the “depart” command. Then the loaded transport vehicle departs. This type of loading operation places enormous demands on the operator of the milling device, who, in addition to the milling process (especially observation of the milling edge, operation and control of the machine during the milling process as well as location of the surroundings of the machine), also has to observe the loading process or the relative position between the transport vehicle and the milling device. This leads to considerable stress to the machine operator.